Quality-Adjusted Life Year Proxies for Caries in Primary Dentition: A Discrete Choice Experiment.

INTRODUCTION: Cost-utility analysis (CUA)-a method to evaluate intervention cost-effectiveness-transforms benefits of alternatives into a measure of quantity and quality of life, such as quality-adjusted life year (QALY), to enable comparison across heterogeneous programs. Measurement challenges prevent directly estimating utilities and calculating QALYs for caries in primary dentition. Proxy disease QALYs are often used as a substitute; however, there lacks quantitative evidence that these proxy diseases are comparable to caries. OBJECTIVE: To employ a discrete choice experiment (DCE) to quantitatively determine the most comparable proxy disease for different levels of caries in primary dentition. METHODS: A cross-sectional DCE survey was administered to respondents (N = 461) who resided in California, were aged ≥18 y, and were primary caretakers for ≥1 child aged 3 to 12 y. Four attributes were included: pain level, disease duration, treatment cost, and family life impacts. Mixed effects logistic regression and conditional logistic regression were used to analyze the survey data. RESULTS: Respondents from the overall sample preferred no pain over mild (odds ratio [OR] = 0.50, P < 0.05), moderate (OR = 0.57, P < 0.05), and severe pain (OR = 0.48, P < 0.05). Acute gastritis (OR = 0.44, P < 0.05), chronic gastritis (OR = 0.31, P < 0.01), and cold sore (OR = 0.38, P < 0.05) were less preferred than stage 1 caries. Acute tonsilitis (OR = 0.43, P < 0.05), acute gastritis (OR = 0.38, P < 0.05), chronic gastritis (OR = 0.26, P < 0.01), and cold sore (OR = 0.33, P < 0.01) were less preferred than stage 2 caries. Chronic gastritis (OR = 0.42,P < 0.05) was less preferred than stage 4 caries. CONCLUSIONS: Parents viewed the characteristics of many diseases with similar QALYs differently. Findings suggest that otitis media and its QALY-as commonly used in CUAs-may be a suitable proxy disease and substitute. However, other disease states with slightly different QALYs may be suitable. As such, the recommendation is to consider a range of proxy diseases and their QALYs when conducting a CUA for child caries interventions. KNOWLEDGE TRANSFER STATEMENT: This study reviews and systematically compares pediatric diseases that are comparable to caries in primary dentition. The findings may inform future research using cost-utility analysis to examine the incremental cost-effectiveness ratio of interventions to prevent and treat caries as compared with an alternative.

What Can We Learn from Parents of Caries-Free and Caries-Active Hispanic Children?

OBJECTIVE: This study evaluated strength-based motivators within Hispanic families that support the creation of health in their children. A mixed-methods approach was used to understand differences in Hispanic parental factors between caries-free (CF) and caries-active (CA) children. METHODS: A cross-sectional survey was conducted with 200 parent-child triads (primary child: between 0 and 6 y; reference child: between 0 and 10 y) recruited from health centers in the Denver Metro area. All the participating children received an oral examination, and the triads were grouped as CF or CA based on the caries status of the primary child. Qualitative data were collected through in-depth individual interviews with the parents. The analysis only involved the primary child. Bivariable analysis were conducted between parent factors (independent variables) and presence or absence of caries (outcome variable). The variables with P < 0.20 in the bivariable analysis were subjected to 2 multivariable logistic regression models. The children in the CF group had mean (SD) age of 2.8 (1.28) y compared to the CA group at 4.0 (1.55) y (P < 0.001). Bivariable analysis demonstrated that parents in the CF group reported higher oral hygiene behavior scores (P = 0.047), perceived fewer barriers (P = 0.009) to accessing preventive dental care, and considered their children more susceptible to cavities (P = 0.001) compared to parents in the CA group. Multivariable model (adjusting for socioeconomic characteristics) demonstrated that parents of CF children perceived high susceptibility to caries for their children (P = 0.040). Multivariable model (adjusting for acculturation) demonstrated an association of parental oral hygiene behavior (P = 0.040) and parent-perceived susceptibility to caries (P = 0.010) with CF child status. Qualitative interviews revealed that parents in the CF group were concerned about their children's higher susceptibility to caries and tried to establish good oral hygiene routines for their children. CONCLUSION: The results of this study demonstrated that parental behaviors and health beliefs could be significant determinants of caries status in Hispanic children. KNOWLEDGE TRANSFER STATEMENT: Results of this study indicate that parental oral health beliefs and behaviors are significant determinants of caries status in children of Hispanic population. Parental beliefs could motivate them to take action or establish behavior that prevents dental caries in their children. Health care providers and caries prevention efforts can incorporate this information to tailor oral health promotional messaging and approaches to improve the oral health of Hispanic children.

Constructing Matched Groups in Dental Observational Health Disparity Studies for Causal Effects.

INTRODUCTION: Electronic health record (EHR) systems provide investigators with rich data from which to examine actual impacts of care delivery in real-world settings. However, confounding is a major concern when comparison groups are not randomized. OBJECTIVES: This article introduced a step-by-step strategy to construct comparable matched groups in a dental study based on the EHR of the Willamette Dental Group. This strategy was employed in preparation for a longitudinal study evaluating the impact of a standardized risk-based caries prevention and management program across patients with public versus private dental insurance in Oregon. METHODS: This study constructed comparable dental patient groups through a process of 1) evaluating the need for and feasibility of matching, 2) considering different matching methods, and 3) evaluating matching quality. The matched groups were then compared for their average ratio in the number of decayed, missing, and filled tooth surfaces (DMFS + dmfs) at baseline. RESULTS: This systematic process resulted in comparably matched groups in baseline covariates but with a clear baseline disparity in caries experience between them. The weighted average ratio in our study showed that, at baseline, publicly insured patients had 1.21-times (95% CI: 1.08 to 1.32) and 1.21-times (95% CI: 1.08 to 1.37) greater number of DMFS + dmfs and number of decayed tooth surfaces (DS + ds) than privately insured patients, respectively. CONCLUSION: Matching is a useful tool to create comparable groups with EHR data to resemble randomized studies, as demonstrated by our study where even with similar demographics, neighborhood and clinic characteristics, publicly insured pediatric patients had greater numbers of DMFS + dmfs and DS + ds than privately insured pediatric patients. KNOWLEDGE TRANSFER STATEMENT: This article provides a systematic, step-by-step strategy for investigators to follow when matching groups in a study-in this case, a study based on electronic health record data. The results from this study will provide patients, clinicians, and policy makers with information to better understand the disparities in oral health between comparable publicly and privately insured pediatric patients who have similar values in individual, clinic, and community covariates. Such understanding will help clinicians and policy makers modify oral health care and relevant policies to improve oral health and reduce disparities between publicly and privately insured patients.

Geography matters: state-level variation in children's oral health care access and oral health status.

OBJECTIVES: To ascertain differences across states in children's oral health care access and oral health status and the factors that contribute to those differences. STUDY DESIGN: Observational study using cross-sectional surveys. METHODS: Using the 2007 National Survey of Children's Health, we examined state variation in parents' report of children's oral health care access (absence of a preventive dental visit) and oral health status. We assessed the unadjusted prevalences of these outcomes, then adjusted with child-, family-, and neighbourhood-level variables using logistic regression; these results are presented directly and graphically. Using multilevel analysis, we then calculated the degree to which child-, family-, and community-level variables explained state variation. Finally, we quantified the influence of state-level variables on state variation. RESULTS: Unadjusted rates of no preventive dental care ranged 9.0-26.8% (mean 17.5%), with little impact of adjusting (10.3-26.7%). Almost 9% of the population had fair/poor oral health; unadjusted range 4.1-14.5%. Adjusting analyses affected fair/poor oral health more than access (5.7-10.7%). Child, family and community factors explained ∼» of the state variation in no preventive visit and ∼½ of fair/poor oral health. State-level factors further contributed to explaining up to a third of residual state variation. CONCLUSION: Geography matters: where a child lives has a large impact on his or her access to oral health care and oral health status, even after adjusting for child, family, community, and state variables. As state-level variation persists, other factors and richer data are needed to clarify the variation and drive changes for more egalitarian and overall improved oral health.

Understanding treatment effect mechanisms of the CAMBRA randomized trial in reducing caries increment.

The Caries Management By Risk Assessment (CAMBRA) randomized controlled trial showed that an intervention featuring combined antibacterial and fluoride therapy significantly reduced bacterial load and suggested reduced caries increment in adults with 1 to 7 baseline cavitated teeth. While trial results speak to the overall effectiveness of an intervention, insight can be gained from understanding the mechanism by which an intervention acts on putative intermediate variables (mediators) to affect outcomes. This study conducted mediation analyses on 109 participants who completed the trial to understand whether the intervention reduced caries increment through its action on potential mediators (oral bacterial load, fluoride levels, and overall caries risk based on the composite of bacterial challenge and salivary fluoride) between the intervention and dental outcomes. The primary outcome was the increment from baseline in decayed, missing, and filled permanent surfaces (ΔDMFS) 24 mo after completing restorations for baseline cavitated lesions. Analyses adjusted for baseline overall risk, bacterial challenge, and fluoride values under a potential outcome framework using generalized linear models. Overall, the CAMBRA intervention was suggestive in reducing the 24-mo DMFS increment (reduction in ΔDMFS: -0.96; 95% confidence interval [CI]: -2.01 to 0.08; P = 0.07); the intervention significantly reduced the 12-mo overall risk (reduction in overall risk: -19%; 95% CI, -7 to -41%;], P = 0.005). Individual mediators, salivary log10 mutans streptococci, log10 lactobacilli, and fluoride level, did not represent statistically significant pathways alone through which the intervention effect was transmitted. However, 36% of the intervention effect on 24-mo DMFS increment was through a mediation effect on 12-mo overall risk (P = 0.03). These findings suggest a greater intervention effect carried through the combined action on multiple aspects of the caries process rather than through any single factor. In addition, a substantial portion of the total effect of the CAMBRA intervention may have operated through unanticipated or unmeasured pathways not included among the potential mediators studied.

Maternal oral bacterial levels predict early childhood caries development.

OBJECTIVE: To calculate the association of maternal salivary bacterial challenge (mutans streptococci [MS] and lactobacilli [LB]) from pregnancy through 24 months' postpartum with child caries incidence (≥1 cavitated or restored teeth) at 36 months. MATERIALS & METHODS: Dental, salivary bacterial, sociodemographic, and behavioral measures were collected at three- to six-month intervals from a birth cohort of low-income Hispanic mother-child dyads (N = 243). We calculated the relative child caries incidence, adjusted for confounding, following higher maternal challenge of MS (>4500 colony-forming units per milliliter of saliva [CFU/mL]) and LB (>50 CFU/mL) based on multivariable models. RESULTS: Salivary MS and LB levels were greater among mothers of caries-affected children versus caries-free children. Mothers with higher salivary MS challenge were more likely to have MS-positive children (>0 CFU/mL), but maternal LB challenge was not a statistically significant predictor of child LB-positive status. Adjusting for sociodemographics, feeding and care practices, and maternal dental status, higher maternal salivary challenge of both MS and LB over the study period predicted nearly double the child caries incidence versus lower MS and LB (cumulative incidence ratio: 1.9; 95% confidence interval: 1.1, 3.8). CONCLUSION: Maternal salivary bacterial challenge not only is associated with oral infection among children but also predicts increased early childhood caries occurrence.

A randomized clinical trial of anticaries therapies targeted according to risk assessment (caries management by risk assessment).

This randomized parallel group clinical trial assessed whether combined antibacterial and fluoride therapy benefits the balance between caries pathological and protective factors. Eligible, enrolled adults (n = 231), with 1-7 baseline cavitated teeth, attending a dental school clinic were randomly assigned to a control or intervention group. Salivary mutans streptococci (MS), lactobacilli (LB), fluoride (F) level, and resulting caries risk status (low or high) assays were determined at baseline and every 6 months. After baseline, all cavitated teeth were restored. An examiner masked to group conducted caries exams at baseline and 2 years after completing restorations. The intervention group used fluoride dentifrice (1,100 ppm F as NaF), 0.12% chlorhexidine gluconate rinse based upon bacterial challenge (MS and LB), and 0.05% NaF rinse based upon salivary F. For the primary outcome, mean caries increment, no statistically significant difference was observed (24% difference between control and intervention groups, p = 0.101). However, the supplemental adjusted zero-inflated Poisson caries increment (change in DMFS) model showed the intervention group had a statistically significantly 24% lower mean than the control group (p = 0.020). Overall, caries risk reduced significantly in intervention versus control over 2 years (baseline adjusted generalized linear mixed models odds ratio, aOR = 3.45; 95% CI: 1.67, 7.13). Change in MS bacterial challenge differed significantly between groups (aOR = 6.70; 95% CI: 2.96, 15.13) but not for LB or F. Targeted antibacterial and fluoride therapy based on salivary microbial and fluoride levels favorably altered the balance between pathological and protective caries risk factors.

Racial and ethnic disparities in disease activity and function among persons with rheumatoid arthritis from university-affiliated clinics.

OBJECTIVE: Health outcomes in rheumatoid arthritis (RA) have improved significantly over the past 2 decades. However, research suggests that disparities exist by race/ethnicity and socioeconomic status, with certain vulnerable populations remaining understudied. Our objective was to assess disparities in disease activity and function by race/ethnicity and explore the impact of language and immigrant status at clinics serving diverse populations. METHODS: We examined a cross-sectional study of 498 adults with confirmed RA at 2 rheumatology clinics: a university hospital clinic and a public county hospital clinic. Outcomes included the Disease Activity Score in 28 joints (DAS28) and its components, and the Health Assessment Questionnaire (HAQ), a measure of function. We estimated multivariable linear regression models including interaction terms for race/ethnicity and clinic site. RESULTS: After adjusting for age, sex, education, disease duration, rheumatoid factor status, and medication use, clinically meaningful and statistically significant differences in DAS28 and HAQ scores were seen by race/ethnicity, language, and immigrant status. Lower disease activity and better function was observed among whites compared to nonwhites at the university hospital. This same pattern was observed for disease activity by language (English compared to non-English) and immigrant status (US-born compared to immigrant) at the university clinic. No significant differences in outcomes were found at the county clinic. CONCLUSION: The relationship between social determinants and RA disease activity varied significantly across clinic setting with pronounced variation at the university, but not at the county clinic. These disparities may be a result of events that preceded access to subspecialty care, poor adherence, or health care delivery system differences.

Mothers' caries increases odds of children's caries.

There are many determinants of children's dental caries. We hypothesized that a mother's untreated caries was associated with increased likelihood of her children's untreated caries, after controlling for other factors. This population-based study was conducted in a rural, primarily Hispanic, California community. Interview and dental examination data for mother-child (children < 18 yrs old) dyads were analyzed. In a Generalized Estimation Equation (GEE) logit model for mothers (n = 179) and children (n = 387), maternal untreated caries was a statistically significant correlate of child's untreated caries, odds ratio (OR) = 1.76 (95%CI: 1.10, 2.70), adjusted for demographic factors. This relationship did not change when behavioral and dental utilization factors were added to the model, OR = 1.85 (95% CI: 1.12, 3.07). Maternal untreated caries almost doubled the odds of children's untreated caries and significantly increased child's caries severity by about 3 surfaces. Caries prevention and dental utilization programs for mothers and their children should be increased.

Dentin caries zones: mineral, structure, and properties.

Caries Detector staining reveals 4 zones in dentin containing caries lesions, but characteristics of each zone are not well-defined. We therefore investigated the physical and microstructural properties of carious dentin in the 4 different zones to determine important differences revealed by Caries Detector staining. Six arrested dentin caries lesions and 2 normal controls were Caries-Detector-stained, each zone (pink, light pink, transparent, apparently normal) being analyzed by atomic force microscopy (AFM) imaging for microstructure, by AFM nano-indentation for mechanical properties, and by transverse digital microradiography (TMR) for mineral content. Microstructure changes, and nanomechanical properties and mineral content significantly decreased across zones. Hydrated elastic modulus and mineral content from normal dentin to pink Caries-Detector-stained dentin ranged from 19.5 [10.6-25.3] GPa to 1.6 [0.0-5.0] GPa and from 42.9 [39.8-44.6] vol% to 12.4 [9.1-14.2] vol%, respectively. Even the most demineralized pink zone contained considerable residual mineral.

Fluoride varnish efficacy in preventing early childhood caries.

To determine the efficacy of fluoride varnish (5% NaF, Duraphat, Colgate) added to caregiver counseling to prevent early childhood caries, we conducted a two-year randomized, dental-examiner-masked clinical trial. Initially, 376 caries-free children, from low-income Chinese or Hispanic San Francisco families, were enrolled (mean age +/- standard deviation, 1.8 +/- 0.6 yrs). All families received counseling, and children were randomized to the following groups: no fluoride varnish, fluoride varnish once/year, or fluoride varnish twice/year. An unexpected protocol deviation resulted in some children receiving less active fluoride varnish than assigned. Intent-to-treat analyses showed a fluoride varnish protective effect in caries incidence, p < 0.01. Analyzing the number of actual, active fluoride varnish applications received resulted in a dose-response effect, p < 0.01. Caries incidence was higher for 'counseling only' vs. 'counseling + fluoride varnish assigned once/year' (OR = 2.20, 95% CI 1.19-4.08) and 'twice/year' (OR = 3.77, 95% CI 1.88-7.58). No related adverse events were reported. Fluoride varnish added to caregiver counseling is efficacious in reducing early childhood caries incidence.

Dental data mining: potential pitfalls and practical issues.

Knowledge Discovery and Data Mining (KDD) have become popular buzzwords. But what exactly is data mining? What are its strengths and limitations? Classic regression, artificial neural network (ANN), and classification and regression tree (CART) models are common KDD tools. Some recent reports (e.g., Kattan et al., 1998) show that ANN and CART models can perform better than classic regression models: CART models excel at covariate interactions, while ANN models excel at nonlinear covariates. Model prediction performance is examined with the use of validation procedures and evaluating concordance, sensitivity, specificity, and likelihood ratio. To aid interpretation, various plots of predicted probabilities are utilized, such as lift charts, receiver operating characteristic curves, and cumulative captured-response plots. A dental caries study is used as an illustrative example. This paper compares the performance of logistic regression with KDD methods of CART and ANN in analyzing data from the Rochester caries study. With careful analysis, such as validation with sufficient sample size and the use of proper competitors, problems of naïve KDD analyses (Schwarzer et al., 2000) can be carefully avoided.

Etching characteristics of dentin: effect of ferric chloride in citric acid.

Citric acid etchants with ferric chloride (10-3) promote adhesion and are effective etchants. We used atomic force microscopy (AFM) to determine the dentin etching characteristics of 10% citric acid etchant with various additions of ferric chloride. AFM was used to measure the surface recession and morphology of dentin etching for a variety of 10% citric + Fe-Cl etchants. Commercial 10-3 was used as the control. Dentin disks were prepared and partially masked during etching so that the unetched dentin served as a reference. AFM images of the same samples were taken at each of the seven experimental steps using 10% citric acid with various quantities of ferric chloride ranging from 0 to 3% (denoted 10-0, 10-1, 10-1.8 and 10-3, respectively) which altered the pH from 1.63 to 0.42. Changes in depth (nm) relative to the reference height for intertubular dentin were determined after etching 15 s; clinical air drying, rewet for 1-5 min; desiccation for 24 h; rehydration for 24 h. Differences of log(depth change) were tested with mixed effects cell mean models. Overall differences were significant (P < 0.001). Significant differences were found between etchants and the extent of collapse on drying was dependent on pH and Fe-Cl content. Following long-term rehydration, samples recovered, but those with 0 or 1% Fe-Cl did not recover as completely (P < 0.01). Etching and collapse depended on Fe-Cl content. The collapse was nearly reversed on rehydration. Ten per cent citric acid with ferric chloride did not prevent the collapse of etched dentin. Ferric chloride additions reduced pH and increased the collapse of dentin on drying for either brief or prolonged periods. Brief rewetting can reverse the effect of brief air drying. For fully desiccated samples the effect was not reversed after 30 s, but was largely or completely reversed at 24 h in solution depending on Fe-Cl content.

Mechanical properties of the dentinoenamel junction: AFM studies of nanohardness, elastic modulus, and fracture.

The dentinoenamel junction (DEJ) is a complex and poorly defined structure that unites the brittle overlying enamel with the dentin that forms the bulk of the tooth. In addition, this structure appears to confer excellent toughness and crack deflecting properties to the tooth, and has drawn considerable interest as a biomimetic model of a structure uniting dissimilar materials. This work sought to characterize the nanomechanical properties in the region of the DEJ using modified AFM based nanoindentation to determine nanohardness and elastic modulus. Lines of indentations traversing the DEJ were made at 1-2 microm intervals from the dentin to enamel along three directions on polished sagittal sections from three third molars. Nanohardness and elastic modulus rose steadily across the DEJ from bulk dentin to enamel. DEJ width was estimated by local polynomial regression fits for each sample and location of the mechanical property curves for the data gradient from enamel to dentin, and gave a mean value of 11.8 microm, which did not vary significantly with intratooth location or among teeth. Nanoindentation was also used to initiate cracks in the DEJ region. In agreement with prior work, it was difficult to initiate cracks that traversed the DEJ, or to produce cracks in the dentin. The fracture toughness values for enamel of 0.6-0.9 MPa . m(1/2) were in good agreement with recent microindentation fracture results. Our results suggest that the DEJ displays a gradient in structure and that nanoindenation methods show promise for further understanding its structure and function.

Demineralization of caries-affected transparent dentin by citric acid: an atomic force microscopy study.

OBJECTIVES: This study determined recession rates of peritubular dentin and intertubular dentin in citric acid solution (0.018M, pH=2.5) for caries-affected transparent dentin, one of the major components of dentin substrate as altered by caries, with comparisons made with non-carious dentin. METHODS: Transparent dentin was identified by sagittally sectioning five obviously carious teeth. Sections were then cut through the transparent dentin area perpendicular to the course of the dentinal tubules. Polished dentin samples of the transparent dentin and non-carious dentin were prepared with an internal reference layer and studied at specific intervals for citric acid etching in an atomic force microscope (AFM). RESULTS: At baseline, transparent dentin was identified by dentinal tubules that were largely occluded with mineral deposits that on etching proved to be acid resistant. Peritubular dentin etched rapidly and linearly over time until it could no longer be measured, yielding etching rates for transparent dentin that could not be distinguished from normal dentin. The normal and transparent intertubular dentin surfaces began etching at nearly the same rate, but then surface recession stabilized after less than 1 microm depth change for both dentin types. SIGNIFICANCE: Most previous studies have focused on demineralization and bonding to normal dentin, although many bonding procedures involve altered dentin substrates, such as those modified by caries. In this study, peritubular and intertubular dentin from normal and caries-affected dentin exhibited similar behavior. The major difference was the presence of acid resistant mineral in most of tubule lumens in the transparent dentin.

Citric acid etching of cervical sclerotic dentin lesions: an AFM study.

Atomic force microscopy (AFM) has been used to determine microstructural changes, etching rates of peritubular dentin, and intertubular dentin recession during demineralization in dilute acidic solutions. These studies have not included many forms of altered dentin, including noncarious sclerotic root dentin associated with Cl V (abfraction) lesions. We sought to determine microstructural changes and recession rates during demineralization in citric acid (pH 2.5, 0.018M) for the transparent/sclerotic zone. Highly polished dentin disks were prepared from teeth with noncarious C1 V lesions (n = 3) and compared with normal root dentin (n = 3). Samples were etched at 5-s intervals for 1 min and at longer intervals up to 30 min. The depth changes in various portions of the dentin with respect to the reference layer were measured and changes in microstructure observed in solution in the wet cell of the AFM. In sclerotic dentin, most tubule lumens were occluded with crystalline deposits that etched more slowly than the other dentin components, but etching rates could not be determined due to their irregular geometry. The intertubular dentin recession quickly reached a plateau after a depth change of <1 microm for all dentin types, in agreement with prior work. Mixed linear regression models indicated an important difference between the etching of sclerotic intertubular dentin and that of non-sclerotic root dentin that became apparent after 600 s (p = 0.037). The sclerotic intertubular dentin underwent less depth change at the plateau (558 nm) compared to normal root dentin (744 nm). In addition, normal root dentin underwent significantly greater recession than coronal dentin (p = 0.002). The results of this study indicate that intertubular sclerotic dentin from Cl V lesions etches differently than normal root dentin, and this may help explain the difficulties in restoring such lesions with current bonding procedures.

A public health vs a risk-based intervention to improve cardiovascular health in elementary school children: the Cardiovascular Health in Children Study.

OBJECTIVES: This study sought to determine the population effects of both classroom-based and risk-based interventions designed to reduce cardiovascular disease risk factors in children. METHODS: Elementary school children (n = 2109; age range: 7-12 years) were randomized by school to a classroom-based intervention for all third and fourth graders, a risk-based intervention only for those with 1 or more cardiovascular disease risk factors, or a control group. The 8-week interventions involved both knowledge--attitude and physical activity components. RESULTS: School-level analyses showed that physical activity in the risk-based group and posttest knowledge in the classroom-based group were significantly higher than in the control group. With regard to trends shown by individual-level analyses, cholesterol dropped more in the classroom-based than in the control group, and skinfold thickness decreased 2.9% in the classroom-based group and 3.2% in the risk-based group (as compared with a 1.1% increase in the control group). CONCLUSIONS: Both classroom-based and risk-based interventions had positive effects on physical activity and knowledge, with trends toward reduced body fat and cholesterol. However, the classroom-based approach was easier to implement and evidenced stronger results than the risk-based intervention.

The relationship between chronic facial pain and a history of trauma and surgery.

OBJECTIVE: Because pain is the most commonly reported symptom of patients presenting to temporomandibular disorders clinics, it is important to identify factors that modify the perception or reality of such pain. The purpose of this study was to investigate the hypothesis that a patient with a history of trauma and/or non-temporomandibular joint surgery might be sensitized to pain and might report increased pain levels if a temporomandibular disorder later developed. STUDY DESIGN: This was a retrospective study of 778 consecutive patients seen over a 1-year period in an Orofacial Pain Clinic. Study parameters included gender, lifetime number of self-reported traumas, lifetime number of non-temporomandibular joint operations, and location, intensity, frequency, and type of temporomandibular disorder-related pain. RESULTS: There were significantly more women than men in the study (609 to 169). There was no relationship between numbers of previous traumas and non-temporomandibular joint operations and types of temporomandibular disorder. However, there were statistically significant relationships between the severity of facial pain and the frequency of facial pain as well as between the severity and frequency of joint pain and the number of traumas. There were also statistically significant associations between the severity and frequency of facial pain and the number of non-temporomandibular joint-related surgical procedures that the patient had undergone. CONCLUSIONS: There is a relationship between a patient's reported history of trauma and/or non-temporomandibular joint-related operations and the severity and frequency of facial and temporomandibular joint pain, should it develop. It is possible that such traumas and operations sensitize the patient in such a way that the pain of subsequent temporomandibular joint disorders is heightened.

Complex sampling: implications for data analysis.

Investigators in dental public health often use strategies other than simple random sampling to identify potential subjects; however, their statistical analyses do not always take into account the complex sampling mechanism. Often it is not clear whether a given strategy requires adjustment for stratification and/or cluster sampling of observations. We propose that the need for such adjustment depends on the primary study objective. As a general rule, we recommend that if the study goal is to estimate the magnitude of either a population value of interest (e.g., prevalence), or an established exposure-outcome association, adjustment of variances to reflect complex sampling is essential because obtaining appropriate variance estimates is a priority. However, if the study goal is to establish the presence of an association, especially in a preliminary investigation of novel conditions or understudied populations, obtaining appropriate variance estimates may not be of primary importance; hence, adjustment of variances for complex sampling is not always required, but often is recommended. This paper describes several types of complex sampling designs, methods of adjusting for complex sampling strategies, examples illustrating the effect of adjustment, and alternative approaches for analysis of complex samples.

AFM study of citric acid-ferric chloride etching characteristics of dentin.

PURPOSE: To determine the etching characteristics of 10% citric acid etchant with 3% ferric chloride (10-3) compared with related etchants without ferric chloride (10-0), or one of similar pH (36% citric acid). MATERIALS AND METHODS: Atomic force microscopy (AFM) was used to measure the surface recession and morphology of dentin. AFM images were taken of the same samples at seven steps of an etching and drying procedure using 10-3 (pH = 1.09), 10-0 (pH = 1.87) or 36% (pH = 1.08) citric acid solutions: at baseline, after etching 15 s, after 5-s air-drying, after rewetting, after 24-hr desiccation, after 30 s rewetting and after 24 hrs rewetting in filtered and purified water. RESULTS: 10-3 etched surfaces receded more than either 10-0 or 36% etched surfaces, and underwent greater collapse on 5-s air-drying. On rewetting all surfaces re-expanded to near their as-etched level. Following prolonged desiccation (24 hrs) all samples collapsed to the level seen after brief air-drying. 30-s rewetting did not restore the surface, but re-expansion of the collapsed collagen matrix was seen at 24 hrs.